The present invention relates to a device for securing the upper terminal position of a lowerable and liftable object, in particular, a spare tire for a vehicle.
Spare tires for vehicles are mostly heavy and bulky objects that, in many vehicles, are accommodated below the vehicle body and are secured against the bottom of the vehicle or against a structure carried by elements of the vehicle chassis. Because of their weight and size, vehicle spare tires can rarely be lowered to the ground, nor raised for storage, by hand. For this reason, heavier vehicles are provided with hoisting devices such as winches, by means of which the spare tire is lowered or raised using a steel cable.
Steel cables, however, are liable to snap or break due to a number of causes, all of which are relevant to their use for the above-mentioned purpose: lack of maintenance, corrosion due to exposure to the environment, fatigue due to vibration-enhanced stresses, and the like. A hoisting cable failure could cause the spare tire to break loose from its anchorage; should this happen in mid-travel, it would seriously endanger not only the vehicle itself, but even more so, other road users behind or alongside it.
A safety device to prevent such accidents is known from U.S. Pat. No. 4,254,939, which provides a device consisting of two hollow uprights, in each of which travels a cable-operated carriage supporting the load to be raised or lowered. In case of cable failure, springs activate a system of levers, causing a roller to be wedged into a tapering gap between the body of each carriage and an inside wall of the uprights. The braking force produced is thus purely frictional.
It is therefore one of the objects of the present invention to provide a device that, in case of cable failure, will prevent the detachment of a load from its point of anchorage by positive action, rather than reliance on friction.
It is a further object of the present invention to ensure that the load is automatically secured once it is raised to its upper position of rest and that it is automatically released from its secured state upon its being controlledly lowered from that position.
According to the invention, the above object is achieved by providing a device for securing the upper terminal position of a liftable and lowerable object, comprising cable means having a hoist-side end and an object-side end; a stationary bracket having an aperture disposed in a substantially horizontal plane; a housing supported by said object-side end of said cable means and carrying said object, said housing having a lower portion and an upper portion, at least the upper portion being configured to pass through said aperture, a first opening at the top of the upper portion and a second opening at the bottom of the lower portion facilitating the passage of said cable means through said housing, and two oppositely located, elongated slots extending along at least parts of said upper portion; lever means located inside, and extending through a substantial portion of, said housing, said lever means being pivotably mounted in the lower portion of said housing and being provided with catch means and camming means, said lever means having a first limit position in which said camming means protrudes through one of said elongated slots, and a second limit position in which said catch means protrudes through the other one of said elongated slots, and spring means adapted to act on said lever means and biasing said lever means towards said second limit position.
The invention further provides a device for securing the upper terminal position of a liftable and lowerable object, comprising cable means having a hoist-side end and an object-side end; a stationary bracket having a rear wall and two lateral walls and provided with bearing means; lever means located between the two lateral walls of said bracket and provided in its upper portion with journals whereby said lever means is pivotably mounted in the bearing means of said bracket and can assume first and second limit positions of tilt, said lever means being provided with gripper means at its lower end; plunger means carrying said object and kinematically connected to said cable means, said plunger means having a central bore through which said cable means passes, and first spring means attached to said stationary bracket and biasing said lever means towards the second limit position; wherein, in the first limit position of said lever means, tension in the cable means causes the lever means to tilt towards the bracket rear wall, thereby permitting said plunger means to enter a space defined by said lever means and said rear wall, thus forcing said lever means into the second limit position with the gripper means of the lever being located substantially vertically below the head of said plunger means, whereby, in case of cable failure, said first spring means forces the lever means into the second limit position and the plunger head is intercepted and retained by said gripper means.